Abrading apparatus



W. A. ROSENBERGER ET AL May 3, w38..

ABRAD I NG APPARATUS Filed Oct. 22, 1935 4 Sheets-Sheet l May 3, 19a8.w. A. osENBERGr-:R ET A1. ZH

ABR/@ING APPARATUS 4 sheetsheet 2 Filed oct. 22, ls

Mii/fer Kader M #XMMS May E, 193%, w. A. RQSENBERGER ET AL ABRADINGAPPARATUS Filed 0G12. 22

, 1955 4 Sheets-Sheet 3' Mew E, H933v W. A. ROSENBERGER `ET AL ABRADINGAPPARATUS Filed oct. 22,1955

4 Sheets-Sheet 4 Patented May 3, 1938 2,116,160 ABRADING APPARATUSWilliam A. Rosenberger and Walter L. Keefer,

Hagerstown, Md., assignors to Panghorn Corporation, Hagerstown, Md., acorporation of Maryland Application october 22,1965, serai No. 46,175

28 laims.

The present invention relates to apparatus for imparting a tumblingaction to castings or other articles of work and simultaneouslysubjecting it to the action of a blast' cleaning stream, and

the so-called inclined barrel type, wherein a barrel is mounted forrotation about an inclined axis and the cleaning medium is directedthrough the open upper end of the barrel upon the work, containedtherein. i

Machines of this general character have been heretofore proposed and arein use today, but they are open to several serious objections. In the`first place, these mills are so designed that it involves a laborious,time-consuming operation to unload them. The barrel must be stopped withthe discharge door uppermost, the door must be manually unlocked and acrane must be used to lift off the door. The barrelis then rotatedthrough 180 to bring the discharge opening facing downwardly, and often`during the discharge of the work, castings are broken by reason of theviolent discharge thereof. The barrel must then be rotated through 180to bring the discharge opening uppermost, the door must then be loweredin place and manually locked. This complicated and time-consuming,operation obviously increases the cost of cleaning thework, oftenresults in broken castings, 36 and prevents anything even remotelyapproaching a continuous blast cleaning operation from being carried outwith the prior machines.

The prior so-called inclined barrel machines now in use today are alsoobjectionable because they fail to uniformly and efliciently clean thework, especially when work of dilferent sizes and shapes are handled,with the result that the work discharged from the barrel must be sortedover and the underblasted pieces returned to the 40 barrel for furthercleaning. Such machines are also diflcult to load and castings or otherwork are often damaged during this operation, either through the natureof the machine or the construction of the loading mechanism employed orIt is accordingly a primary object of this inventionto provide a novelinclined barrel abrading machine that will efficiently clean castingslor other work of various sizes and shapes without 50 breaking them andat the same time clean them more thoroughly and more rapidly thanheretofore possible.

It is a further-major` object of this invention to provide an inclinedtumbling barrel, having a 55 discharge door and operating mechanismwhich it is particularly concerned rwith machines of makes it possibleto open the door for workdischarging purposes and again close it with asingle stop of thelbarrel.

Another object is to provide tumbling barrels of the character rotatableabout an inclined axis, with a door and door operating assembly which isoperable to completely control the discharge of Work from the barrels,thereby precluding breakage of even fragile pieces of Work, and yeteffecting a complete discharge of all the pieces of Work contained inthe barrels.

It is a further object to provide a tilted mill having a discharge doorand a door operating assembly for the door that is operable to unlockthe door and control its opening operation thereof so as to do away withall manual operations, and which is also provided with interlockingcontrol mechanism for preventing the discharge operations from beingcarried out in improper sequence.

A further object of this invention is to provide an inclined barrelabrading machine having a mechanical device for projecting abrasive intothe barrel at abrading velocities for efficiently cleaning the workcontained therein, and which is so mounted as to not interfere withloading and unloading of the barrel.

It is another object of this invention to provide an inclined barrelabrading machine having a device for loading it rapidly and which isoperable to drop the work a minimum distance, thereby precluding damageto even fragile pieces v of Work.

- Our invention also aims to provide Va machine for simultaneouslytumbling and abrading work having a novel abrasive reconditioning andrecirculating mechanism built into the machine and forming a partthereof.

A further object is to provide an abrading machine of the characterhaving an inclined barrel, with a power operated discharge door,designed to be unlocked, opened and closed without any manual operationswhatsoever.

It is another object to provide an abrading machine having an inclinedtumbling barrel embodying novel improved work turning, barrel supportingand driving, dust-sealing and removing, wear preventing, andWork-charging and discharging features.

Further objects of the invention will become apparent as thespecification proceeds in connection with the annexed drawings, and fromthe appended claims.

1n the drawings:

Figure 1 is a perspective view of an abrading machine embodying theinvention, and in this figure the barrel is shown stopped in dischargingposition and the loading mechanism is shown in lowered position ready toreceive a load.

Figure 2 is a perspective view of our machine and illustrates the doorand the door operating mechanism, with the barrel stopped indischargingposition, but with the door locked and with the restraining bar ininoperative position.

Figure 3 is a longitudinal sectional view through the barrel of themachine shown in Figure l and also illustrates a part of the housing andthe manner in which the abrasive projecting mechanism is relatedthereto. Figure 3A is a perspective view, with parts broken away, of thebarrel bottom.

Figure 4 is a diagrammatic view illustrating the tumbling barrel of themachine, shown in Figure 1 and the abrasive propelling device that ispreferably employed in combination therewith.

1Figure 5 is an enlarged view of one of the latch bar assemblies andillustrates the manner in which it cooperates with the lugs of thedischarge door.

Figure 6 is a view of the top portion of the loading mechanismpreferably employed with our machine and also forming part of thisinvention and it illustrates the work loading bucket in dotted lines andin work discharging position'.

Figure 7 is a fragmentai sectional view taken substantially on line I-lof Figure 3, looking in the direction of the arrows.

Figure 8 is an elevational view o f the abrasive cleaning orreconditioning mechanism of the invention.

Figure 9 is an elevational view illustrating the manner in whichabrasive is conveyed from the elevator to the abrasive projecting wheel.

Figure 10 is a diagrammatic view illustrating one form of mechanism forcontrolling the `operation of our abrading machine.

Figure 1l is a longitudinal section view of a modified form of barrelforming part of our invention. s

Figure 12 is a top plan view of the barrel shown in Figure 11 andFigures 13 and 14; 15 and 16 are views similar lto Figures 11 and 12respectively, but illustrate further forms of barrels of this invention.

With continued reference to the drawings, wherein like referencecharacters have been employed to designate like parts throughout the'several views thereof, and with the particular Loading device The workhandled by the barrel, irrespective of whether it be castings or otherarticles to be abraded, is preferably loaded into the barrel by means ofthe loading device now to be described., Although the machine willemciently abrade and discharge the work when the work is loaded in thebarrel by hand or by other forms of loading mechanism, we preferablyemploy the one illustrated as it is combined with the machine in a novelmanner, rendering the machine compact and easy to operate, and it ispeculiarly capable of loading the work in the barrel in such manner .asto avoid breaking or otherwise damaging even fragile castings.

With reference to Figures 1 and 6, the loading or barrel charging devicecomprises a pair of upright channel members I0, joined at their lowerends by a member I'I and which terminate In curved portions I2 at theirupper ends. Channel. members I0 are braced with respect to each otherand with respect to the machine housing E by a plurality of structuralmembers I3 and I4 respectively as seen in Figure 1. Mounted for guidedmovement onl channel members I0 is a work-lifting bucket or receptacleI5, carrying rollers I6 upon stub shafts IT. Rollers I6 ride In theflanges of members I0. As seen in Figure 1, when the work bucket isdisposed in lowered position it is located at such a height that workmay be readily placed therein. The upper edge of bucket I5 is preferablyinclined for cooperation with the stationary barrel top or hood as willappear hereinafter.

The work bucket is elevated by means of a motor I8 and a speed reducingmechanism I9, connected to a shaft 2| by means of a sprocket chain drive22. Shaft 2l is journalled upon the top of cabinet E in any suitablemanner, and wound upon spirally grooved drums mounted near both ends isa pair of chains 23 and 24. Chains 23 and 26 pass over a pair of pulleys25 and 26 supported upon a pair of arms 2l on members I9 and framemembers I3 and are secured to shafts I7 of each lower roller I6.

To the front of housing E is secured a generally circular stationary topor hood 28 for the open upper end of the barrel, and pivoted thereto isa gasket-equipped cover 29 which closes a work charging opening 30therein. Cover 29 is preferably synchronously opened when work bucket I5is raised into discharging position by a chain 3l secured to cover 29 at32 and which is wound upon the middle portion of shaft 2| between chains23 and 2| as seen in Figure l.

With bucket I5 loaded with work, motor I8 is started to rotate shaft 2Iand thereby wind chains 23 and 24 upon it and lift the bucket upwardlyin guides I0. yAfter the bucket is moved upwardly a predetermineddistance, the slack in chain 3I is taken up by reason of the chainwinding upon shaft 2|. When the-slack is taken up door 29 starts to openand when bucket I5 has reached a predetermined position in guides I0,the door 29 has been elevated to a position to allow bucket I5 to swingtherepast into the position shown in Figure 6, with the result that thework is discharged into the barrel. When the bucket is disposed in itsupper position it is inclined downwardly as seen in Figure 6 togravitationally charge the work into the barrel, and in the appendedclaimsthe term"inverted" is in' tended to apply to this condition of thebucket.

When it is desired to lower-the bucket. motor I8 is reversed so as tounwind chains 23, 24, and 3l from shaft 21|. In vorder to assist bucketI5 around the curved portion of guides I0, we prefpush bucket I5 back inthe guides to a position where the weight ofthe bucket itself willrestore it to its initial position adjacent the floor.

It is accordingly seen that we have provided a loading device that takesup a minimum of door space, is spaced from the front of the barrel toprovide adequate discharge space, is easily operated, is coordinatedwith the machine to automatically open the door thereof as it approachesbarrel-charging position, and is operable to lift the entire charge ofwork into closed proximity to the barrel before the work is dumped intothe latter whereby the work flows into the barrel at low velocity,thereby precluding damage to the fragile castings or other pieces ofwork.

Tumbling barrel and dm'ng mechanism therefor Before proceeding to thedescription of the barrel proper, it is desired to briefly describe theconstruction of housing E, seen in. Figure 1. The front edge of housingE terminates in a pair of angle iron members 38, each of which is/offset at its lower portion to provide a maximum working space in frontof the machine. Although the Work discharged from barrel B may becarried away in any suitable manner, as for instance, by means of apower operated conveyor or the like, we have shown a container F mountedupon a seriesof conveying rollers 39 mounted in a frame 4l. In order toguide the work from the barrel into box E, a. short chute 42 is providedwhich has an inner edge conforming to the shape of the barrel and ismounted at its front edge upon `a support 43 extending between andsecured to angle iron uprights 38. As seen in Figure 1, adequate spaceis provided between the lower part `of the housing and supports I8 toenable barrel housing 54 which is solidly mounted upon supports 55 and56 mounted in housing E. Bearing 52 takes the radial load of the upperend of shaft 5I and thrust bearing 53 takes the radial and thrust loadsat theplower end of shaft 5I. A worm wheel 51 is rigidlysecured to shaft5l for cooperation with a worm V58 journalled in casing ,54. Worm 58 maybe driven in any suitable manner, but it preferably is driven by meansof an electric motor through a `speed reducer so as to produce acomparatively low rate of rotation of the barrel. If desired a speedchanger may be associated with the driving mechanism or the motor-speedmay be changed to provide different speeds of rotation of the barrel. Asseen in Figure 3, spider 48 terminates in a skirt in which a sealingmember 60 is provided. Member 68 sealingly cooperates with the outersurface of support 54 to preclude escape of lubricant or entrance ofabrasive.

Bottom 46 of the barrel is provided with a plurality of abrasive drainholes 6| through which abrasive is conveyed to the abrasive cleaningmechanism. The abrasive draining through holes 6I falls into a pan-hizeelement 62 secured to the drum and having a plurality of abrasivelifting vanes 63 secured thereto (Figure 7). The

abrasive lifted by vanes 63, through rotation of the drum, falls into achute 64 having a lip 65 extending into the space between the inneredges of the blades. Inorder to prevent the escape of abrasive thatmight drop from the vanes before they reach chute 64, we have provided abifurcated chute 66, which passes around spider 48 and extends inside ofmember 62 at its lower end to thereby convey any escaping abrasive backinto the lower vanes to be again lifted into discharge position. TheabrasiveV is conveyed through chute 64 into an abrasive cleaning orreconditioning mechanism to be hereinafter described.

The work may be tumbled directly upon barrel bottom 46 if desired, butwe preferably provide the barrel with an inclined false bottom which hasbeen found to impart a superior tumbling action to the work. The bottomis made up of a skeleton frame 68 and an auxiliary floor or liner 69which is preferably made in two senilcircular segments for ease ofremoval andreplacement. A work lifting and turning member 10 is alsopreferably secured in place over the segments of floor 69. 'Frame 68comprises a plurallty of blocks 1|, which are welded at their outeredges to barrel 45 and are carried by supports 1|.I welded to barrelbottom 46. To the under sides of blocks 1| are welded shelves 68A whichare spaced from the lower side of floor 69 by the thickness of blocks 1Iwhen the oor is in place. Floor 69 is detachably secured to blocks 1l byany suitable means such as screws. A front liner 14, having a curvedpiece 14A and a pair of bars 14B welded to its bottom'surface, isdetachably secured to bottom 46 in any suitable manner and cooperateswith floor 69 to define the barrel bottom. The front edge of oor 69rests upon bars 14B. Mounted between the removable and permanent oors inany suitable manner, as for instance by means of a plurality of supports14C, are a plurality of weights 13, which are employed to compensate forthe weight of the discharge door and thus statically balance the barrelabout its axis.

The margin of floor 69 and liner 14 is provided with a plurality ofabrasive drain holes 15, and the drain holes in liner 14 are preferablycircumferentially offset frpm the drain holes 6| in permanent bottom 46,so that nails, wires and like refuse'e'ntering holes 15 will not dropthrough bottom 46, andyet the abrasive will drop through holes 6| and becarried into the abrasive cleaner. In a similar manner, shelves 68Aprevent nails and the like from dropping through the openings '15 infloor 69, and yet they permit the abrasive to slide over their inneredges onto bottom 46. Although we have described the support for oor 69as being a built'upi structure it may be made rality of abrasive drainholes 18, and a labyrinth-v forming flange 19 which is secured to barrelB by a spacing and reenforcing member 8D. The llower edge of hoodstructure 28 is`provided with a pair of labyrinth-forming flanges 9|,which are disposed in spaced concentric overlapped relationship to theupper edge of the barrel and flange 19 to deiinea tortuous passage andthereby preclude escape of' abrasive from thebarrel. abrasive findingits way into the space between the upper edge of the barrel and fiange19 automatically drains back into the barrel through openings 18 whenthey reach their upper position, lifters 18 being provided behind eachdrain hole to prevent the trapped abrasive from sliding back.

It is accordingly seen that we have provided a tumbling barrel, which,by reason of its support in dust-proof bearings solely at one end, takesup but little space at its periphery and has a long life. l

Any suitable form of abrasive throwing or propelling mechanism, forinstance, an air blast nozzle assembly or a mechanical abrasive throwingdevice of any characterv may be associated with a tumbling barrel forcleaning the work therein, but we preferably employ a mechanical devicecomprising a bladed wheel whose axis is,

substantially horizontal and preferablyV` parallel to a vertical planecontaining the axis of rotation of the barrel. With reference to Figures3 -and 4, the centrifugal wheel comprises a base 83; a housing84; anabrasive feed conduit 85 having a discharge slot 86 therein; a rotor 811having a plurality of impeller blades 88 and a plurality of propellerblades 89 secured thereto, the impeller blades being located withinconduit 85 and operable to discharge the abrasive outwardly throughopening 86 onto the inner ends of blades 89; and a feed spout 9i..`Rotor 81 is mounted on a shaft and is adapted to be rotated at acomparatively high speed. By reason of the construction of thecentrifugal wheel, it discharges all of the abrasive fed thereto at highabrading velocities downwardly upon the tumbling work in the mannergenerally indicated in Figures 3 and 4, and it is apparent that thefanlike abrasive discharge is operable to efficiently clean the work asit cataracts upon itself in the barrel. Because of the particular`manner in which the centrifugal wheel is mounted in the housing andrelated to the barrel, it does not interfere with the loading orunloading operations in any way. f.

' Discharge door and operating means therefor As seen in Figures 1 and2, the discharge door is of curved shape to conform to the shape of theba'rrel, and it comprises a door proper 93 and a removable andreplaceable liner 94 (Figure 3) detachably secured thereto.

The exterior of door 93 is provided with external reenforcing flanges 92and with a re- 'straining-bar-receiving assembly comprising a bracket 95providing a pair of spaced ears 96 inwhich a detent 91 is pivoted.Detent 91 is urged upwardly by a compression spring 98 (Figure 3), andits upward movement is limited by pin 99 connected to a link |00pivoted'to detent 31., The bracketalso provides a plate defining anabutment face'which cooperates with the restraining bar in a manner tobe hereinafter pointed out.

Door 93 is pivotally connected to, the upper edge of barrel B by meansof a pair of links |02, which are preferably pivoted to flange 19 tothere- A by derive rigid'support by reason of reenforcing Any v v thedoor.

anarco i 4sary for the operator to perform any manual latching orunlatching operation whatsoever. This structure will now be described.

With reference to Figures 2 and 5, a pair of upper andrlower latch lugs|05 and |06 respectively are secured to door 93 and cooperate with apair of latch members |01 and |08 secured to a latch bar |09 mounted forreciprocation on barrel B by means of a pair of apertured lugs and H2. Acompression spring ||3 encircles bar |09 and bears against lug and latchmember |08 to urge bar |09 downwardly, so as to urge latch members |01and |08 into latching cooperation with lugs |05 and |06, respectively,and lugs |05 and |06 are preferably provided wlth inclined faces ||4 sothat spring ||3 is capable of exertinga powerful closing action upon thedoor.

An identically similar latching assembly is provided on the other edgeof door 93, and in order to simplify the disclosure it has not beenshown and the description of it will not be given.

Journalled inthe lower end of each latch bar |09 is a roller ||6, eachof which is adapted to cooperate with an unlatching cam or fingerrigidly secured to a shaft I8 journalled in housing E in any suitablemanner. With reference to Figure 2, a lever 9 is secured to shaft IIBand is connected to a piston rod |2|. Rod |26 cooperates with aconventional piston and cylinder assembly designated generally as |22,having a conduit |23 connected with a suitable source of compressed air.The flow of air to assembly |22 is controlled in a manner to behereinafter described, and by admitting air to cylinder |22, rod |2| ispulled inwardly and lever ||9 is rocked clockwise (Figure 2) therebycausing cams ||1 to lift bars |09 against the action of springs ||3 andunlocking the door.

Opening and closing movements of the discharge door are positivelycontrolled at all times by a restraining bar or operating bar assembly.Pivotally secured to the front of housing E are a pair of links |25 and|26 which are pivotally connected at their lower ends to a pair ofrestraining bars |21 and |28 respectively and a restraining bar |29. Bar|29, when swung about the upper ends of links |25 and |26 as an axis.contacts detent 91, rocking it downwardly and engaging abutment plate|0|. When bar |29 contacts plate |0| detent 91 rises behind it and thusyieldingly but firmly holds it in position against When bar |29 has beenbrought into engagement with the door as just described, and when thedoor has been unlatched, theA door may be swung outwardly, the doorbeing supported by bar |29 undergoes a lifting action as it opens byreason ofl bar |29 and swinging about the axis of links |25 and |26.

Bar |29 may be actuated into door opening and door closing positions byany suitable means, but we preferably provide bars |21 and |28 withteeth |3|, and mesh them with a pair of pinions |32 carried by a shaft|33. Shaft |33 is driven by motor |34 or any other suitable prime movereither directly or through a speed reducing mechanism. Motor |34 isprovided with a conventional push button stop-start control and alsoincluded in the circuit are limit switches automatically actuated bymovements of bars |21 and |28 into their extreme door opening and doorclosing positions (not shown) toautomatically break the motor circuit.

l Any suitable form of control mechanism may be employed for controllingthe circuits of the various motors and for operating the valve for thedoor unlatching cylinder, and for interlocking the parts so that theycannot be improperly ac tuated, but we preferably use a control assemblyof the character diagrammatically illustrated in Figure 10, which hasproven-to be entirely satisfactory in our device. With continuedreference `to Figure 10, a hand lever |36 is pivotally sup` ported inany suitable manner upon housing E and carries at its upper end a switchassembly |31 comprising a pair of contacts |38 and |39, which areadapted to be electrically connected by a T shaped contact arm |4|carrying a roller |42 and urged into contacting position by-al spring|43. Lever |36 is adapted to be swung into the dotted line positionillustrated in Figure 10 wherein itl may cooperate with a cam |44adjustably carried by'barrel B.- Contacts |38 and |39 are connected inseries with the circuit of the motor employed to drive the barrel, andwhich is designated diagrammatieally as |45. Motor |45 is also con-,nected to a push button start-stop control circuit having start andstop buttons |41 and |48 respectively, mounted in a switch block |49.

When it vis desired to stop the barrel for discharging, lever |36 isrocked into the dotted line position shown in Figure 10, and when thebarrel is brought approximately into discharging position, cam |44 willengage roller |42 and push con`- tact arm |4| into the dotted linecircuit breaking condition indicated in Figure 10. The current for motor|45 is accordingly cut off and if desired an automatic brake may beemployed to quickly stop the barrel when the circuitis broken. Magneticbrakes are well known in the art, for` instance, they are usedonelevators and comprise a spring engaged brake, which is held in releasedposition by magnets energized by the motor circuit, and a brake of thischaracter may be ernployed for stopping the barrel in dischargingposition, and the appended claims are intended to embrace the inventionwhenI it assumes this form. When it is desired to restart, the barrellever |36 is swung into its full line position and button |41 is pushedto make the circuit ofmotor Also mounted on lblock |49 are push-buttons|5| and |52 which are connected to the circuit of motor |34, asindicated 'at |53. By pushing button |5|, motor |34 rotates in adirection to move restraining bar |29 outwardly, whereas pushing button|52 causes motor |34 to move bar |29 inwardly.

In view of the fact that it is undesirable to have bar |29 disposedinwardly when the barrel is rotating, as the barrel would strike it eachrevolution, we preferably provide a device for preventing push buttons|5| and |52 from being aetuated unless the barrel is in dischargingposi.

tion, and this mechanism preferably assumes the form of a plate |54mounted for reciprocation on base |49 by a plurality of guides |55 andhaving apertures |56, |51, |58, and |59 provided therein. Plate |54 ispreferably connectedto hand lever |36 by means of a link |6|, sothatwhen lever |36 is swung into dotted line position, plate |54 is moved tothe right into the dotted line position indicated.

As illustrated in Figure 10, plate |54 is disposed in its left handposition, with the result that' |29, cannot be actuated unless handlever |36 is rocked into dotted line barrel stopping position shown inFigure 2. Conversely, when lever |36 is disposed in its dotted lineposition, plate |54 covers the push buttons for motor |45, with theresult that motor |45 cannot be restarted while plate |54 is disposed ina position to expose buttons |5| and |52 for motor |34.

In order to prevent the discharging door from being unlocked when thebar |29 is disposed in its outer position, which would result in aviolent discharge of work from the barrel, we have provided a shaft |63,suitably journalled on housing E in any suitable manner, and having alever |64 secured thereto. Lever |64 is mounted in the housing so as tolie in the path of movement of link 25, and the parts so designed thatwhen bar |29 is moved into the inner position in rm contact with door93, link will engage lever |64 and rock it into the dotted line positionshown in Figure 10.

The compressed air supplied cylinder |22 is controlled by a valve |65connected to conduit |23 having an operating handle |66, which, whenswung into its dotted line position, will open conduit |23 and allow theassembly |22 to rock shaft ||9 into door unlocking position. When handle66 is disposed in its full line position, valve |65 places cylinder |22in communication with the atmosphere. Rigidly mounted on shaft |63 is asegment-shaped member |61, which in the. full line position shownprecludes valve handle |66 swinging into open position, or if handle |66is disposed in the dotted line position, segment |61 prevents moving thevalve into closed position. Also secured to shaft |63 is a lever |68which is connected to a plate |69 by means of a link |1|. Plate |69 ismounted for sliding movement on plate |49 by means of guides |12 and isprovided with openings |13 and |14, which in the position shown,register with control buttonsl |41 and |48 for motor |45. Plate |69 isalso provided with a finger |15 adapted to seat in a recess |16 providedin plate |54.

Assuming that hand lever |36 has been moved into its-dotted lineposition, and that the barrel is stopped in discharge position, button|52 may be pressed to cause motor |34 to bring bar |29 into abuttingcooperation .with the door. When bar |29 is moved into this position,link |25 will have rocked shaft |63 into dotted line position to bringsegment |61 out the path of movement of valve lever |66. `Accordingly,valve |66 may now be rocked into its dotted line position to energizecylinder |22 and unlock the discharge door. Button |5| 4may now beoperated to cause motor |34 vto move bar |29 into its outer position andallow the work to be discharged from the drum.

As soon as bar |29 has been moved in a slight distance, it will allowlever |64 to Abe restored to its full-line position, thereby bringingsegment |61 into the position shown in Figure 10 to accordingly preventlatch bars |69 from being rocked into locking position while the door isaway from the discharge opening. When the work has been discharged fromthe barrel, button |5| is pushed to cause motor |34 and bar |29 to bringthe door into closed position. When thedoor is completely closed link|25 rocks shaftY When the parts are in the discharge position justdescribed, with the door open, it is impossible to start the barrelbecause shaft |63, in rocking into the dotted line position, bringsplate |69 into its upper dotted line position, with finger |15 inengagement with recess |16. Engagement of finger |15 with plate |54through link |8| prevents hand lever |36 from being rocked back into itsfull line position and therefore it is impossible to start the barrelwhile the door is open. When shaft |63'is disposed in its full lineposition, itis also impossible for the operator to'tamper with thedevice and attempt to rotate shaft |63 by grasping parts |64 or |61,because finger |15 -will engage the side edge of plate |54 and lock theparts, A

It'is therefore apparent that the control mec anism of our machineprovides truly a push-button control of all operations and yet the partsareI so interlocked as to render it entirely foolproof.

Abrasive reconditioning and recirculation Although any suitablemechanism may be employed to take the abrasive from chute 64 (Figure 3)and free it Afrom dust and casting fragments or other extraneous matterand return it to the centrifugal Wheel, we preferably employ themechanism shown in Figures 8 and 9 for this purpose, as it has proved tobe lentirely satisfactory. With continued reference to these figures, animperforate drum |8| is mounted for rotation in housing E inA anysuitable manner, as for instance by means of rollers |82. The right-handend of the drum is open, and the left-hand end of the drum is providedwith an end plate having an opening |83 therein. Mounted within drum |8|and spaced from-the walls thereof is a cylinn drical screen |84 having ahelical refuse-propelzijn charges it at |89..

refuse which is ltoo large to pass through the ling element |85 securedto its inner wall. -Screen |84 projects beyond the right end of drum |8|and is adapted to discharge refuse therefrom into a chute |86, whichleads to a suitable receptacle or container.

Chute 64, associated with barrel B is provided with a spout portion |81which projects into drum |8| for discharging the spent abrasive uponscreen |84. Secured to the inner wall of drum |8| is a helical abrasivepropelling/member |88 which is the result that as spent abrasive is fedthrough/ spout |81 and dischargedinto screen |84, it is agitated anddust developed by the agitation is drawn fromy left to right into hood|94, and thence to the fan and dust collector. The cleaned abrasivedrops into the space between drum |8| and screen |84, and is propelledby helical member |88 to the right end of the drum which dis- Theextraneous matter or esh or screen |84 is propelled to the right endfof-'the screen by member |85, where it is dis- '.charged'into chute|86.

A part of the air drawn into the suction fan just described is drawnthrough an opening in cover 28 (not shown) through a separateventilating connection suitably baffled to prevent excessive amounts ofabrasive entering the ventilating system. By drawing air from barrel B`a slight sub-atmospheric pressure is developed therein, which causes airto be sucked into the barrel through the labyrinth at the top of thebarrel, thereby precluding escape of dust into the room where themachine is located. The air is sucked into the abrasive reconditioningsystem at the junction of chute 64 with the barrel B and the junction ofspout |81 with drum 18|, thereby preventing dust from escaping at thesepoints.

Opefatio'n The work to be cleaned is loaded into bucket |5 with theparts in the position shown in Figure 1, and wherein the bucket isconveniently loaded for easy handling. If desired, bucket I5 may be madedetachable so that it may be loaded elsewhere and inserted in themachine during the time that another load is being cleaned. Forinstance, the four roller assemblies may be mounted in a cradle to whichbucket I5 may be detachably connected- Also, members I8 may be extendeddownwardly into a pit, so as to bring the upper edge of bucket |5approximately level with the floor, and thereby permit easy dumping ofwork into it from a wheelbarrow or the like.

After the bucket |5 has been loaded, motor |8 is operated tosimultaneously raise the bucket and lift cover 29. As the bucket reachessubstantially work unloading or barrel charging position it dischargesthe work into the barrel, and in view of the fact that the bucket isclosely adjacent the barrel before it is inverted, the castings or workpass into the barrel with a minimum initial velocity, thereby minimizingthe possibility of breaking fragile castings or the like during theloading operation. After the loading operation is completed, motor I8isreversed to restore bucket I5 to the lower part of guides I0 as in themanner previously described. In connection with the loading operation,it should be particularly observed that by reason of the construction ofthe machine ready access is provided for the loading bucket therebymaking it easy to load it, and the bucket completely discharges its loadin a single operation, doing away with the necessity for anydoor-opening or other preparatory operations.

Cleaning After the work has been loaded into the barrel in the mannerjust described, and assuming that hand lever |36 is disposed in its fullline position shown in Figure 10, with door 93 closed, button |41 may bepushed to start barrel motor |45, because plate |54 uncovers the controlbuttons for this motor under these conditions. The operator then starts`the suction fan associated with the abrasive reconditioning drum andalso starts the motor which drives rotor 81 of the centrifugal wheel.After the centrifugal wheel has been brought up to speed, the abrasiveis admitted to spout 9| to start the abrasive blast stream. The work isnow being simultaneously tumbled or cataracted upon itself within barrelB, and the blast of abrasive is `being directed upon it generallyas'indicated in Figures 3 and 4, where it is seen that a fan-like streamof abrasive is discharged into the drum. As the barrel rotates the workis picked up by the inclined oor, assisted vby piece 10, and thrown andgravitated at a given velocity through the blast stream toward the lowercylindrical wall, depending upon the position of the barrel. When thebarrel is in the position shown in Figure 3, the work will rapidlygravitate from the inclined floor, whereas when the inclined bottomy isdisposed in a position 180 removed, the work will migrate at a lowerrate of speed. It is therefore apparent that the work is eflicien'tlytumbled and blasted, and although we prefer to use an inclined bottom inthe barrel, it is to be understood 'that any form ofthe barrel bottommay bel employed without detracting from the other features of themachine. For instance, work turning or tumbling pieces of other formsmay be built up on the floor of the barrel, or if desired the end of thebarrel may be pressed into a suitable formation to properly tumble thework. Moreover, although we have shown the barrel floor as constitutinga false bottom, it is to be understood that the barrel end 46 may beomitted and the spider 48 directly connected to frame 68 if desiredwithout departing from the spirit of the invention.

When it is desired to stop the cleaning opera-l tion and discharge work,the abrasive is cut off from spout 9|, the centrifugal wheel is stopped,and hand lever |36 is moved into the dotted line position shown inFigure 10, with the result that barrel B4 only makes part of a completerevolu- Ition before it brings cam |44 into cooperation with roller |42and breaks the circuit of motor as previously described. In thisconnection it is observed that as cam |44 is secured to ,barrel B bybolts passing through slotted holes thereinA (not shown) the location ofthe cam may be varied so as to var'y the point at which the i |54, isnow pushed to bring `bar |29 into cooperating engagement with the door,as previously described. 'Ihis action automatically swings segment |61out of the way and air valve handle |66 may now be rocked into thedotted line posil tion shown in Figure 10 to unlock the door. When thedoor has been unlocked in this manner it is nevertheless held in securecontact with drum B by bar |29.

With the parts in the position just described, button |.i| is nowdepressed to allow door 93 to swing into open position under theinfluence of gravity and under the control of motor |34. Motor |34positively controls the rate at which the door is opened, irrespectiveof how heavy the particular load may be; The work contained in thebarrel is accordingly discharged over apron 42 into receptacle F at lowvelocity. The circuit for motor |34 is preferably equipped with astart-stop push button control (not shown) in order that the door maybealternately opened andstopped so as to open the door by increments andpositively control the discharge of work from the barrel. If desired, aspeed controlling means may be embodied in circuit of motor |34 in orderto 'open the door at various speeds.

With the discharge door moved into open posi- *L tion in the manner justdescribed, it is impos- "sible 'to actuate the valve handle |66 andbring llowfer position unless"'door 93 is in completely |29 between itsdoor-opening and door-closing positions. With this structure it will beunnecessary to reverse motor |34 to effect the doorclosing anddoor-opening operations as bars |21 and |28, as they attain one extremeposition, will pass dead center and start a reverse movement.

Moreover, latch bars |09 may be provided with automatic trips toautomatically maintain them in raised position during the periods thatdoor 93 is swung away from the barrel, and the appended claims areintended to embrace our mechanism when it assumes this form.

Since the door 93 is pivoted about a compound arrangement of two axes,namely the axes of links |25 and |26 and the shaft |03, the top of thedoor does not swing outwardly on a small radius but opens much morewidely as it opens by rising under the lifting action of link |25 and|26. This is a very desirable feature especially when large castings ofawkward shapes are handled by the machine. If desired,` however, undersome conditions door 93 may behinged to barrel B at its top, one of itssides or its bottom edges without sacrificing the advantages of re;straining bar |29 and its operating mechanism.

While the cleaning operation just described is being carried out, thespent abrasive, -together with dust and other sufficiently smallmaterial dislodged by the work drains through the holes in the barreloors and is picked up by the lifting vanes carried by the barrel anddischarged into the cleaning drum, Where it is cleaned and the abrasivereturned to the centrifugal wheel or other abrasive propelling device,as previously described.

The parts are preferably so designed that when the machine is stoppedthe abrasive elevator is also stopped, so that when the machine is againstarted, a uniform flow of abrasive will be fed to the wheel. When. themachine is stopped it should be observed that as the lower'edge of thedischarge opening is substantially flush with the floor of the barrel,any refuse too large to pass through the drain holes in the barrel willbe discharged from the machine when door 93 is opened.

In Figures 11 to 16 inclusive we have illustrated modied forms of barrelbottoms which may be used with the machine just described, and theselection of a particular bottom will, of course, depend upon the natureof the work handled by the machine and the tumbling action desired.

In Figure l1, barrel B is provided with an inclined bottom 20|, similarto the auxiliary bottom of the machine first described, upon which is.mounted a pyramid-shaped work lifting and turning member' 202, thepyramid preferably having four sides` as seen in Figure l2. In Figure 12the relation of member 202 with respect to 'door 93 is shown.

The barrel B 'shown in Figures 13 and 14 is provided with a cone-shapedbottom 203, and mounted thereupon, preferably diametrically oppositethedischarge door 93 of the barrel, is a work lifting and turning member204, which is secured to the inner wall of barrel B and to the uppersurface of oor 203. Two members 204 may be used if desired.

In Figures and 16 we have shown a barrel B having a two-part bottomcomprising sections 205 and 206, which are made in 4halves as seen inFigure 16. Sections 205 and 206 have different degrees of inclination,thereby providing a step 201 over which the work is abruptly tumbledonceeach revolution of the barrel. The barrel is preferably rotated in adirection to cause the work to tumble down over step 201, but ifdesired, it may be rotated in the opposite direction to cause the workto tumble up, or be lifted by step 201.

In all of the forms of tumbling barrel bottom assemblies described it isto be understood. that the sizes and proportions of the work turning andlifting pieces may be varied to suit the particular work and the desiredcondition involved. Also the inclination of the oors may be increased ordecreased as desired.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription,

`and all changes which comewithin the meaning fand range of equivalencyof the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and Ian opentop, means for rotating said barrel to cause it to tumble work containedtherein, the upper edge of said barrel terminating in at least twoupstanding annular flanges, a stationarily supported hood structuremounted adjacent the top of said barrel and having at least onedownwardly extending annular flange disposed in overlapped nested butspaced relationship to the flanges of said barrel for preventingextraneous material from escaping from said barrel, said barrel beingprovided with a plurality of passages communieating with the interior ofsaid barrel and with the space between the flanges on said barrel, forreturning extraneous material to the barrel inter1or.

2. In an abrading machine, a generally cylindrical barrel mounted forrotation abviut an axis disposed at a considerable angle with `inehorizontal, said barrel having an open top and a closed bottom, powermeans for rotating said barrelto tumble work contained therein, astationarily s upported hood structure mounted adjacent the top of saidbarrel and closing the upper end thereof, said hood structure providinga charging door through which work may be charged into the barrel, adischarge door'pivotaily connected to said barrel and forming a part ofthe cylindrical wally o the barrel, said barrel being operable togravitationally discharge its contents when it is stopped in a dischargeposition with said discharge .door disposed below the axis of rotationof the barrel, and said discharging door is open, and means for openingand closing said door when said barrel is disposed in said dischargeposition, whereby said barrel may be unloaded and loaded with a singlebarrel stop.

3. The abrading machine described in claim 2, together with selectivelyoperable means for causing said power means to automatically stop saidbarrel in discharge position.

4. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and open top,power means for rotating said barrel to thereby tumble work locatedtherein, said barrel having a discharge opening located in thecylindrical wall thereof through which said work may gravitationallydischarge, a discharge door adapted to close said discharge opening,latch means carried by said barrel for locking said discharge door inclosed position; and stationarily supported means locatedv adjacent saidbarrel .for selectively operating said latch means to unlock said door.

5. 'Ihe abrading machine described in claim 4, wherein said stationarilysupported means is so constructed as to only cooperate with said latchmeans and unlock said door when said barrel is disposed in apredetermined discharge position.

6. The abrading machine described in claim 4, together with stationarilysupported means for cooperating with said door and controlling its\opening movement under the influence of gravity.

7. In an abrading machine, a, generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and an opentop, power means for rotating said barrel to thereby tumble work locatedtherein, said barrel having a discharge opening in the cylindrical wallthereof through which saidwork may gravitationally discharge, adischarge door pivotally connected to said barrel and operable to closesaid discharge opening, latch means carried by said barrel and operableto lock said door in closed position, stationarily supported meansmounted adjacent said barrel for selectively operating said latch meansto unlock said door when said barrel is disposed in a predetermineddischarge position, and means for preventing said last named means frombeing operated until said barrel is disposed in discharge position.

8. 'I'he abrading machine described in claim 7, together withcontrolling means, ymovable into cooperating relationship with saiddoor, for controlling movement thereof toward open position under theiniiuence of gravity, and having means for preventing said door frombeing unlocked until said controlling means is moved into cooperatingrelationship with said door.

. 9. 'Ihe abrading machine described in claim 7, together with means forpreventing said barrel from being rotated by said power means when saiddischarge door is unlocked.

10. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and an opentop, power means for rotating said barrel to thereby tumble workcontained therein, said barrel having a discharge opening in thecylindrical wall thereof through which said work may be gravitationallydischarged, a discharge door pivoted atits upper end to said barrel andoperable to close said discharge opening, latch means carried by saidbarrel for locking said door in closed position, means, stationarilysupported adjacent said barrel, for operating said latch means to unlocksaid door, and restraining means, movable into engagement with saiddoor,

for controlling movement thereof towards open position under the actionof the load of the work' control the rate of discharge of work from saidbarrel.

11. The abrading machine described in claim 10, wherein said door isconnected to said barrel by at least one link member, and saidrestraining element is operable to support said door when it isopened'and for compelling said doorgto rock about a shifting horizontalaxis remote from said link member.

12. In an abrading machine, an open ended barrel mounted for rotationabout an inclined axis for tumbling work contained therein, a hoodstructure supported adjacent the open end of saidbarrel and having acharging opening therein through which work may be charged into thebarrel, a cover mounted on said hood and operable to close saidchargingopening, a charging device comprising a receptaclel mounted for movementfrom a loading position to an unloading position adjacent said chargingopening, power means for lifting said receptacle into loading position,and means, controlled in accordance with movements of said receptacle,for opening said cover as said receptacle is brought into unloadingposition.

13. In an abrading machine,- a generally cylindrical barrel mounted for'rotation about an inclined axis and having an open top and a closedbottom, an inclined hood structure mounted adjacent, and overlying thetop of said barrel and sealingly associated therewith, said hoodstructure having an upper opening and a lower opening provided therein,said lower opening dening a barrel-charging opening and having a doorcooperating therewith, Va mechanical abrasive pivotally connected tosaid barrel and operable to close said discharge opening, means forlocking said door in closed position, and restraining means forcontrolling movement thereof toward open position under the action ofthe load of the work contained in said barrel, comprising a bar mountedfor movement toward and away from said barrel and movable intoengagement with a portion of said door, and selectively controlled powermeans for controlling the rate of movement of said bar away from saidbarrel, to thereby control therate of opening of said door under theinuenoe o the work contained in said barrel.

16. The abrading machine described in claim 15, wherein said bar ispivoted for rocking movement about a substantially horizontal axisadjacent said barrel, and wherein said bar and power means areoperableto move said door into closed position.

17. The abrading machine described in claim 15, wherein said bar ismounted for rocking.

to thereby tumble work contained therein, saidl barrel having adischarge opening in the `cylindrical wall thereof through which saidwork may be gravitationally discharged, a discharge door propellingmechanism mounted above said hood ..l3 iv0td at its upper end t0 Saidbarrel and Opelstructure and operable to discharge at least one streamof abrasive through said upper opening 'r 1d. In an abrading machine, agenerally cylindrical barrel mounted for rotation about an inclined axisand having a closed bottom and an open top, means for' rotating saidvbarrel to tumble work contained therein, said barrel bottom comprisinga work supporting floor of substantially plane conguration and oi"comparatively large area, said floor being disposed at an angle to aplane normal to the axis of said barrel, to cause work contained thereinto move rapidly acrossv the barrel bottom when the latter is disposed inone position and to effect a less rapid migration of work afcross thebarrel bottom when said barrel is Idisposed in a second position, the

cylindrical wall 'of said barrel beingqprovided drical barrel mountedfor rotation about an inclined axis and Vhaving a closed bottom and anopen top, power means for rotating said barrel to thereby tumble workcontained therein, said barrel having a discharge opening in thecylindrical wall thereof through which Work may be gravitationallydischarged, a. discharge door able to close said discharge opening,latch means .carried by said barrel for locking said doorin'closedypositiom comprising means for forcing each side edge of saiddoor against said barrel, and

means for simultaneously unlatching said latching means. A

19. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and an opentop, power means for rotating said barrel to thereby tumble workcontained therein, said barrel having a discharge opening in thecylindrical wall thereof through which said work may be gravitationallydischarged, a discharge Y'door pivotally connected to said barrel andoperable to close said discharge opening, latch means carried by saidbarrel for locking said door in closed position, comprising at least onelatch bar mounted for sliding movement longitudinal- 1y of the barrel'and engageable with one side edge of said door, resilient means forurging said` 4latch bar toward latching position, and means A for movingsaid latch bar into unlatching position against the action of saidresilient means.

20. The abrading machine described in claim 19, wherein said last-namedmeans comprisesa `shaft.l mounted for rocking movement adjacent saidbarrel and having a cam portion engageable with said latch bar formoving the latter longitudinally of the barrel against the action ofsaid resilient means when it is rocked in one direction, said shaftbeing movable to vbring it out of the path of rotation of saidvbarrel toy avoid interfering with the latter. I

21. In an abrading machine, a, generally cy. Iindrical barrel mountedfor rotation about an inclined axis and having a closed bottom `and anopen top, power means for 'rotating said barrel to thereby tumble :workcontained therein,

said barrel having a discharge opening in the cylindrical wall thereofthrough which said work may be gravitationally discharged, a dischargedoor pivoted at its upper end to said barrel and operable to close saiddischarge opening, said door being connected to said barrel by means ofat least one link member which is pivoted to the door and to the barrel,said door having a downwardly facing abutment, a bar member mounted formovement toward and away from said barrel and adapted to cooperate withsaid abutment for controlling movement of said door toward open positionunder the action of the load of work contained in said barrel, said doorbeing adapted to be supported on said bar member by said abutment wallwhen said door is being opened, for compelling said door to rock about ashifting horizontal axis, and means for yieldingly coupling said door tosaid bar member when it is engaged therewith.

22. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and an opentop, an inclined floor assembly mounted in said barrel and supported bythe closed bottom thereof, power means for rotating said barrel tothereby tumble work contained therein, said floor assembly beingsupported on a plurality of standards connected to said closed bottom, aplurality of connecting members bridging the upper ends of saidstandards but being spaced below said floor, said floor having aplurality of apertures therein adjacent the margin thereof, andoverlying said connecting members.

23. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having a closed bottom and an opentop, barrel means for rotating said barrel to thereby tumble workcontained therein, said barrel having a discharge opening in thecylindrical wall thereof through which said work may be gravitationallydischarged, .a discharge door pivoted to said barrel and operable toclose said discharge opening, and at least one counterweight secured tosaid barrel at a point substantially diametrically opposite said door,for

counter-balancing the weight of the latter. 4

24. In an abrading machine, a tumbling barrel having a discharge doormounted for movement toward and away therefrom, latching means forholding said door in closed position, restraining means engageable withsaid door for controlling the opening movement thereof, means forpreventing said barrel from being rotated when said door is in openposition, and means for preventing saidlatching means from being movedinto latching position when restraining means is engaged with said doorand the latter is in open position.

25. The abrading machine' described in claim 24, wherein said latchingmeans embodies a fluid pressure, valve-control mechanism for releasingit, and said restraining means is provided with an interlockingmechanisml for preventing said valve-from being operated into latchingposition when said restraining means and said door are in open position.

26. In 'an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having an open top and a closedbottom, an inclined hood structure mounted adjacent, and overlying thetop of the barrel and secured to a stationary support, said hoodstructure having an elongated opening provided therein adjacent theupper edge of said barrel, a mechanical abrasive propelling mechanismmounted upon said hood structure and operable to discharge a stream ofabrasive through said elongated opening in said hood and upon the workcontained in said barrel, said abrasive propelling mechanism embodying arotor mounted for rotation about a substantially horizontal axisandwhich is substantially parallel to a vertical plane containing ytheaxis of said barrel, said abrasive projecting mechanism being operableto project a fan-shaped stream of abrasive into the barrel at an angleof approximately ninety degrees to said vertical plane.

27. In an abrading machine, a housing structure comprising a top wall, arear wall and a pair of side Walls, a generally cylindrical turnblingbarrel disposed in said housing structure and mounted for rotation aboutan axis which is inclined considerably to the horizontal, said axisbeing inclined toward the iront of said housing structure, said barrelhaving a closed bottom and an open top and adapted to tumble workcontained therein when it is rotated, said barrel having a door openingin the cylindrical wall thereof together with a door mounted formovement in the open position, said housing having an inclined frontwall disposed approximately normal to the axis of said barrel andcovering the open top of the latter, said housing side walls havingtheir front edges relieved so as to dispose them rearwardly of the upperpart of the barrel, to provide a large space defining a barreldischarging station and being sufficiently large to allow a container tobe placed below the level of the bottom of said barrel for receivingwork for gravitating therefrom when said barrel door is opened.

28. In an abrading machine, a generally cylindrical barrel mounted forrotation about an inclined axis and having an open top, means locatedadjacent the opentop of said barrel for projecting abrasive upon work asit cataracts upon itself in said barrel, said barrel having a closedbottom for supporting the work, said bottom having a plurality ofapertures therein through which spent abrasive may drain, means locatedbelow said bottom for preventing elongated objects from passing throughsaid apertures, an elevator structure disposed below the bottom of saidbarrel and secured to said barrel for synchronous rotation therewith,said elevator structure providing a plurality of abrasive receivingpockets into which said abrasive may gravitate from said apertures, saidpockets being operable to discharge their abrasive when they attain apredetermined position above the axis of said barrel, stationarilysupported chute means for conveying abrasive as it is discharged fromsaid pockets to an abrasive cleaning mechanism, a hood structuresealingly associated with the upper edge of said barrel but being spacedtherefrom, means for drawing air currents between said hood structureand the upper edge of said barrel for removing dust from said barrel andfor preventing leakage of dust into the atmosphere at the top of thebarrel, and means forv drawing air currents through said chute means.

WM. A. ROSENBERGER.

WALTER L. KEEFER.

